The invention relates generally to threaded fasteners, and more particularly to screw thread configurations therefor and combinations thereof.
Threaded fasteners having relatively low pressure flank angles are known generally, as disclosed for example in U.S. Pat. No. 2,827,820 entitled xe2x80x9cSelf-Tapping Screwsxe2x80x9d.
An object of the present invention is to provide novel threaded fasteners and screw thread configurations therefor that improve upon and overcome problems in the art.
Another object of the invention is to provide novel threaded fasteners and screw thread forms therefor that are reliable and economical.
A further object of the invention is to provide novel threaded fasteners and screw thread configurations therefor having improved performance and manufacturability.
Another object of the invention is to provide novel threaded fasteners and screw thread forms therefor having improved strip torque and pull-out strength.
Another object of the invention is to provide novel threaded fasteners having relatively low driving torques.
Yet another object of the invention is to provide novel threaded fasteners and thread configurations therefor having both improved strip torque and pull-out strength characteristics and relatively low driving torques.
Still another object of the invention is to provide novel case hardened threaded fasteners having improved strip torque and pull-out strength characteristics.
Another object of the invention is to provide novel threaded fasteners having improved strip torque and pull-out strength, some of which that may be manufactured using conventional thread forming processes.
A more particular object of the invention is to provide novel threaded fasteners comprising a shaft having a screw thread with a pressure flank disposed about at least a portion thereof, the pressure flank having a first pressure flank angle on a radial inner portion thereof and a second pressure flank angle on a radial outer portion thereof, the first pressure flank angle between approximately 5 degrees and approximately 10 degrees, the second pressure flank angle greater than the first pressure flank angle.
Another more particular object of the invention is to provide novel screw thread forms comprising a screw thread having a pressure flank with a first pressure flank angle on a radial inner portion thereof and a second pressure flank angle on a radial outer portion thereof, the first pressure flank angle less than the second pressure flank angle.
These and other objects, aspects, features and advantages of the present invention will become more fully apparent upon careful consideration of the following Detailed Description of the Invention and the accompanying Drawings, which may be disproportionate for ease of understanding, wherein like structure and steps are referenced generally by corresponding numerals and indicators.